GEN BIO 4TH SEM: Evolution and Origin of Biodiversity

Evolution and Origin of Biodiversity

• Evolution is the change in properties of groups of organisms over generations.
• Charles Darwin proposed that all species of life descended from a common ancestor.

Theory of Evolution

• Evolution is the process by which modern organisms descended from ancient organisms.
• A theory is a well-supported, testable explanation of natural phenomena.

Natural Selection and Artificial Selection

• Natural selection is the selection process that occurs due to an organism’s ability to adapt to its surroundings.
• Artificial selection is the selective breeding imposed by humans to enhance desirable features.

Lamarck's Theory of Evolution

• Tendency toward perfection (e.g., giraffe necks)
• Use and disuse (e.g., birds using forearms)
• Inheritance of acquired traits

Mechanisms of Genetic Variation

• Mutation: alteration in the nucleic acid sequence of the genome of an organism.
• Genetic drift: a random process that can lead to large changes in populations over a short period.
• Gene flow: transfer of genetic material from one population to another.
• Non-random mating: organisms mate with others of the same or different genotypes.

Genetic Variation

• Neutral: no problem
• Maladaptive: abnormalities
• Beneficial: increases fitness and mate selection
• Genetic variation can occur through mutation, gene flow, and sexual reproduction.

Hardy-Weinberg Theory

• The genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.
• Factors that can disturb the equilibrium: mutation, natural selection, non-random mating, genetic drift, and gene flow.

Evidence of Evolution

• Fossil record: shows change over time
• Geographic distribution of living things: similar environments have similar types of organisms
• Homologous body structures: develop from the same embryonic tissue
• Similarities in early development
• Vestigial organs: serve no useful function in an organism

Taxonomy

• Branch of biology that groups and names organisms based on their characteristics.
• Carolus Linnaeus is considered the Father of Modern Taxonomy.
• Aristotle developed the first widely accepted system of biological classification.
• Binomial nomenclature: a standard two-part system for naming organisms.
• Specific epithet: describes a characteristic of the organism.
• Taxa: Linnaeus’ hierarchical system of classification includes 7 levels.